The propagation characteristics of nonlinear ion–acoustic（IA） solitary waves（SWs） are studied in thermal electron–positron–ion plasma considering the effect of relativistic positron beam. Starting from a set of...The propagation characteristics of nonlinear ion–acoustic（IA） solitary waves（SWs） are studied in thermal electron–positron–ion plasma considering the effect of relativistic positron beam. Starting from a set of fluid equations and using the reductive perturbation technique, we derive a Korteweg–de Vries（KdV） equation which governs the evolution of weakly nonlinear IA SWs in relativistic beam driven plasmas. The properties of the IA soliton are studied, and it is shown that the presence of relativistic positron beam significantly modifies the characteristics of IA solitons.展开更多
A rigorous theoretical investigation is made of ion-acoustic shock structures in an unmagnetized three-component plasma whose constituents are nonextensive electrons, nonextensive positrons, and inertial ions. The Bur...A rigorous theoretical investigation is made of ion-acoustic shock structures in an unmagnetized three-component plasma whose constituents are nonextensive electrons, nonextensive positrons, and inertial ions. The Burgers equation is derived by employing the reductive perturbation method. The effects of electron and positron nonextensivity and ion kinematic viscosity on the properties of these ion-acoustic shock waves are briefly discussed. It is found that shock waves with positive and negative potentials are obtained to depend on the plasma parameters. The entailment of our results may be useful to understand some astrophysical and cosmological scenarios including stellar polytropes, hadronic matter and quark-gluon plasma, protoneutron stars, dark-matter halos, etc., where effects of nonextensivity can play significant roles.展开更多
Electron-acoustic shock waves （EASWs） in an unmagnetized four-component plasma （containing hot elec- trons and positrons following the q-nonextensiv.e distribution, cold mobile viscous electron fluid, and immobile ...Electron-acoustic shock waves （EASWs） in an unmagnetized four-component plasma （containing hot elec- trons and positrons following the q-nonextensiv.e distribution, cold mobile viscous electron fluid, and immobile positive ions） are studied in nonplanar （cylindrical and spherical） geometry. With the help of the reductive perturbation method, the modified Burgers equation is derived. Analytically, the effects of nonplanar geometry, nonextensivity, relative number density and temperature ratios, and cold electron kinematic viscosity on the basic properties （viz. amplitude, width, speed, etc.） of EASWs are discussed. It is exarmined that the EASWs in nonplanar geometry significantly differ from those in planar geometry. The results of this investigation can be helpful in understanding the nonlinear features of EASWs in various astrophysical plasmas.展开更多
Ion-acoustic solitary (IAS) waves in electron-positron-ion (e-p-i) plasma have been of interest to many researchers probably due to their relevance in understanding the Universe. However, the study of non-linear ion-a...Ion-acoustic solitary (IAS) waves in electron-positron-ion (e-p-i) plasma have been of interest to many researchers probably due to their relevance in understanding the Universe. However, the study of non-linear ion-acoustic waves in e-p-i plasma with non-thermal electrons has not been adequately studied. A theoretical investigation on non-linear IAS waves in e-p-i plasma comprising of warm inertial adiabatic fluid ions and electrons that are kappa distributed, and Boltzman distributed positron is presented here using the Sagdeev potential technique. It was found that existence domains of finite amplitude IAS waves were confined within the limits of minimum and maximum Mach numbers with varying k values. For lower values of k, the amplitude of the solitary electrostatic potential structures increased as the width decreased, while for high values, the potential amplitude decreased as the width of the solitary structure increased.展开更多
The space-time evolution of a given density perturbation in cold homogeneous electron- positron-ion plasma is investigated with an assumption of infinitely massive ions by employing a numerical calculation method. The...The space-time evolution of a given density perturbation in cold homogeneous electron- positron-ion plasma is investigated with an assumption of infinitely massive ions by employing a numerical calculation method. The phase-mixing time and wave-breaking time can be effectively distinguished with this method. It is found that an increase of the ratio of equilibrium ion density to equilibrium electron density can attenuate plasma oscillations, leading to a delay in wave breaking. The dependence of the phase-mixing and wave-breaking times on the amplitude of the initial perturbation is also discussed.展开更多
The nonlinear propagation of waves (specially solitary waves) in an ultra-relativistic degenerate dense plasma (containing ultra-relativistic degenerate electrons and positrons, cold, mobile, inertial ions, and negati...The nonlinear propagation of waves (specially solitary waves) in an ultra-relativistic degenerate dense plasma (containing ultra-relativistic degenerate electrons and positrons, cold, mobile, inertial ions, and negatively charged static dust) have been investigated by the reductive perturbation method. The linear dispersion relation and Korteweg de-Vries equation have been derived whose numerical solutions have been analyzed to identify the basic features of electrostatic solitary structures that may form in such a degenerate dense plasma. The existence of solitary structures has been also verified by employing the pseudo-potential method. The implications of our results in astrophysical compact objects have been briefly discussed.展开更多
This paper discusses the existence of ion-acoustic solitary waves and their interaction in a dense quantum electron positron-ion plasma by using the quantum hydrodynamic equations. The extended Poincar^-Lighthill-Kuo ...This paper discusses the existence of ion-acoustic solitary waves and their interaction in a dense quantum electron positron-ion plasma by using the quantum hydrodynamic equations. The extended Poincar^-Lighthill-Kuo perturbation method is used to derive the Korteweg-de Vries equations for quantum ion-acoustic solitary waves in this plasma. The effects of the ratio of positrons to ions unperturbation number density p and the quantum diffraction parameter He （Hp） on the newly formed wave during interaction, and the phase shift of the colliding solitary waves are studied. It is found that the interaction between two solitary waves fits linear superposition principle and these plasma parameters have significantly influence on the newly formed wave and phase shift of the colliding solitary waves. The investigations should be useful for understanding the propagation and interaction of ion-acoustic solitary waves in dense astrophysical plasmas （such as white dwarfs） as well as in intense laser-solid matter interaction experiments.展开更多
The formation and propagation of shocks and solitons are investigated in an unmagnetized, ultradense plasma containing degenerate Fermi gas of electrons and positrons, and classical ion gas by employing Thomas-Fermi m...The formation and propagation of shocks and solitons are investigated in an unmagnetized, ultradense plasma containing degenerate Fermi gas of electrons and positrons, and classical ion gas by employing Thomas-Fermi model. For this purpose, a deformed Korteweg-de Vries-Berger （dKdVB） equation is derived using the reductive perturbative technique for cold, adiabatic, and isothermal ions. Localized analytical solutions of dKdVB equation in planar geometry are obtained for dispersion as well as dissipation dominant cases. For nonplanar （cylindrical and spherical） geometry, time varying numerical shock wave solution of dKdVB equation is found. Its dispersion dominant case leading to the soliton solution is also discussed. The effect of ion temperature, positron concentration and dissipation is found significant on these nonlinear structures. The relevance of the results to the systems of scientific interest is pointed out.展开更多
The basic properties of the nonlinear propagation of the nonplanar （cylindrical and spherical） positronacoustic （PA） shock waves （SHWs） in an unmagnetized electron-positron-ion （e-p-i） plasma containing immobi...The basic properties of the nonlinear propagation of the nonplanar （cylindrical and spherical） positronacoustic （PA） shock waves （SHWs） in an unmagnetized electron-positron-ion （e-p-i） plasma containing immobile positive ions, mobile cold positrons, and superthermal （kappa distributed） hot positrons and electrons are investigated both analytically and numerically. The modified Burgers equation （roBE） is derived by using the reductive perturbation method. The basic features of PA SHWs are significantly modified by the cold positron kinematic viscosity （U）, superthermal parameter of electrons （ke）, superthermal parameter of hot positrons （kp）, the ratio of the electron temperature to hot positron temperature （or）, the ratio of the electron number density to cold positron number density （μe）, and the ratio of the hot positron number density to cold positron number density （μph）. This study could be useful to identify the basic properties of nonlinear electrostatic disturbances in dissipative space and laboratory plasmas.展开更多
Interfacial interactions between rough mineral particles have garnered considerable attention as they directly determine particle agglomeration and floatability.This study comprehensively investigates the agglomeratio...Interfacial interactions between rough mineral particles have garnered considerable attention as they directly determine particle agglomeration and floatability.This study comprehensively investigates the agglomeration characteristics of siderite particles after argon(Ar)plasma surface modification through settling tests,flocs size measurements,and fractal dimension calculations.Ar plasma surface modification promotes the agglomeration of siderite particles,as evidenced by increased floc size and density.The agglomeration mechanism induced by Ar plasma surface modification is evaluated using a theoretical model combining the surface element integration(SEI)approach,differential geometry,and the composite Simpson's rule.Changes in surface roughness,wettability,and charge are considered in this model.Compared to the unpretreated siderite particles,the energy barrier for interaction of the 30-min Ar plasma-pretreated siderite particles decreases from 2.3×10-^(17)J to 1.6×10^(-17)J.This reduction provides strong evidence for the agglomeration behavior of siderite particles.Furthermore,flotation experiments confirm that Ar plasma surface modification is conducive to the aggregation flotation of siderite.These findings offer crucial insights into particle aggregation and dispersion behaviors,with notable application in mineral flotation.展开更多
This study investigated enhancing the wear resistance of Ti6Al4V alloys for medical applications by incorporating Ti C nanoreinforcements using advanced spark plasma sintering(SPS). The addition of up to 2.5wt% Ti C s...This study investigated enhancing the wear resistance of Ti6Al4V alloys for medical applications by incorporating Ti C nanoreinforcements using advanced spark plasma sintering(SPS). The addition of up to 2.5wt% Ti C significantly improved the mechanical properties, including a notable 18.2% increase in hardness(HV 332). Fretting wear tests against 316L stainless steel(SS316L) balls demonstrated a 20wt%–22wt% reduction in wear volume in the Ti6Al4V/Ti C composites compared with the monolithic alloy. Microstructural analysis revealed that Ti C reinforcement controlled the grain orientation and reduced the β-phase content, which contributed to enhanced mechanical properties. The monolithic alloy exhibited a Widmanstätten lamellar microstructure, while increasing the Ti C content modified the wear mechanisms from ploughing and adhesion(0–0.5wt%) to pitting and abrasion(1wt%–2.5wt%). At higher reinforcement levels, the formation of a robust oxide layer through tribo-oxide treatment effectively reduced the wear volume by minimizing the abrasive effects and plastic deformation. This study highlights the potential of SPS-mediated Ti C reinforcement as a transformative approach for improving the performance of Ti6Al4V alloys, paving the way for advanced medical applications.展开更多
The nonlinear features of two-dimensional ion acoustic(IA) solitary and shock structures in a dissipative electron-positron-ion(EPI) quantum plasma are investigated. The dissipation in the system is taken into account...The nonlinear features of two-dimensional ion acoustic(IA) solitary and shock structures in a dissipative electron-positron-ion(EPI) quantum plasma are investigated. The dissipation in the system is taken into account by incorporating the kinematic viscosity of ions in plasmas. A quantum hydrodynamic(QHD) model is used to describe the quantum plasma system. The propagation of small but finite amplitude solitons and shocks is governed by the Kadomtsev-Petviashvili-Burger(KPB) equation. It is observed that depending on the values of plasma parameters(viz.quantum diffraction, positron concentration, viscosity), both compressive and rarefactive solitons and shocks are found to exist. Furthermore, the energy of the soliton is computed and possible solutions of the KPB equation are presented numerically in terms of the monotonic and oscillatory shock profiles展开更多
The highly efficient manufacturing of atomic-scale smooth β-Ga_(2)O_(3)surface is fairly challenging because β-Ga_(2)O_(3)is a typical difficult-to-machine material.In this study,a novel plasma dry etching method na...The highly efficient manufacturing of atomic-scale smooth β-Ga_(2)O_(3)surface is fairly challenging because β-Ga_(2)O_(3)is a typical difficult-to-machine material.In this study,a novel plasma dry etching method named plasma-based atom-selective etching(PASE)is proposed to achieve the highly efficient,atomic-scale,and damage-free polishing of β-Ga_(2)O_(3).The plasma is excited through the inductive coupling principle and carbon tetrafluoride is utilized as the main reaction gas to etch β-Ga_(2)O_(3).The core of PASE polishing of β-Ga_(2)O_(3)is the remarkable lateral etching effect,which is ensured by both the intrinsic property of the surface and the extrinsic temperature condition.As revealed by density functional theory-based calculations,the intrinsic difference in the etching energy barrier of atoms at the step edge(2.36 eV)and in the terrace plane(4.37 eV)determines their difference in the etching rate,and their etching rate difference can be greatly enlarged by increasing the extrinsic temperature.The polishing of β-Ga_(2)O_(3)based on the lateral etching effect is further verified in the etching experiments.The Sa roughness of β-Ga_(2)O_(3)(001)substrate is reduced from 14.8 nm to 0.057 nm within 120 s,and the corresponding material removal rate reaches up to 20.96μm·min^(−1).The polished β-Ga_(2)O_(3)displays significantly improved crystalline quality and photoluminescence intensity,and the polishing effect of PASE is independent of the crystal face of β-Ga_(2)O_(3).In addition,the competition between chemical etching and physical reconstruction,which is determined by temperature and greatly affects the surface state of β-Ga_(2)O_(3),is deeply studied for the first time.These findings not only demonstrate the high-efficiency and high-quality polishing of β-Ga_(2)O_(3)via atmospheric plasma etching but also hold significant implications for guiding future plasma-based surface manufacturing of β-Ga_(2)O_(3).展开更多
目的:观察Plasma等离子束联合强脉冲光治疗面部烧伤瘢痕的疗效及对瘢痕评分、疼痛程度的影响。方法:本次研究为前瞻性研究,采用随机数字表法将茂名市人民医院2024年3月至2024年8月期间收治的92例面部烧伤瘢痕患者分为对照组(接受强脉冲...目的:观察Plasma等离子束联合强脉冲光治疗面部烧伤瘢痕的疗效及对瘢痕评分、疼痛程度的影响。方法:本次研究为前瞻性研究,采用随机数字表法将茂名市人民医院2024年3月至2024年8月期间收治的92例面部烧伤瘢痕患者分为对照组(接受强脉冲光治疗,46例)和研究组(对照组的基础上接受Plasma等离子束治疗,46例)。对比两组疗效、相关量表评分、瘢痕恢复情况和不良反应发生率。结果:和对照组治疗后相比,研究组的临床总有效率和中文版简易烧伤健康量表(chinese version of the simplified burn health scale, BSHS-B)评分更高,温哥华瘢痕量表(vancouver scar scale, VSS)、视觉模拟疼痛量表(visual analogue scale, VAS)评分和瘢痕厚度、瘢痕血流灌注量更低(P<0.05)。两组不良反应发生率组间对比未见差异(P>0.05)。结论:应用Plasma离子束联合强脉冲光治疗面部烧伤瘢痕患者,可提高临床疗效,改善瘢痕厚度和血流灌注量,缓解瘢痕瘙痒及疼痛程度,安全性较好。展开更多
The effects of plasma screening on the ^(1)P^(o) resonance states of H-and He below the n=3 and n=4 thresholds of the respective subsystemsare investigated using the stabilization method and correlated exponential wav...The effects of plasma screening on the ^(1)P^(o) resonance states of H-and He below the n=3 and n=4 thresholds of the respective subsystemsare investigated using the stabilization method and correlated exponential wave functions.Two plasma mediums,namely,the Debye plasma and quantum plasma environments are considered.The screened Coulomb potential(SCP)obtained from Debye-Hückel model is used to represent Debye plasma environments and the exponential cosine screened Coulomb potential(ECSCP)obtained from a modified Debye-Hückel model is used to represent quantum plasma environments.The resonance parameters(resonance positions and widths)are presented in terms of the screening parameters.展开更多
Objective:Based on multistage metabolomic profiling and Mendelian randomization analyses,the current study identified plasma metabolites that predicted the risk of developing gastric cancer(GC)and determined whether k...Objective:Based on multistage metabolomic profiling and Mendelian randomization analyses,the current study identified plasma metabolites that predicted the risk of developing gastric cancer(GC)and determined whether key metabolite levels modified the GC primary prevention effects.Methods:Plasma metabolites associated with GC risk were identified through a case-control study.Bi-directional two-sample Mendelian randomization analyses were performed to determine potential causal relationships utilizing the Shandong Intervention Trial(SIT),a nested case-control study of the Mass Intervention Trial in Linqu,Shandong province(MITS),China,the UK Biobank,and the Finn Gen project.Results:A higher genetic risk score for plasma L-aspartic acid was significantly associated with an increased GC risk in the northern Chinese population(SIT:HR=1.26 per 1 SD change,95%CI:1.07±1.49;MITS:HR=1.07,95%CI:1.00±1.14)and an increased gastric adenocarcinoma risk in Finn Gen(OR=1.68,95%CI:1.16±2.45).Genetically predicted plasma L-aspartic acid levels also modified the GC primary prevention effects with the beneficial effect of Helicobacter pylori eradication notably observed among individuals within the top quartile of L-aspartic acid level(P-interaction=0.098)and the beneficial effect of garlic supplementation only for those within the lowest quartile of L-aspartic acid level(P-interaction=0.02).Conclusions:Elevated plasma L-aspartic acid levels significantly increased the risk of developing GC and modified the effects of GC primary prevention.Further studies from other populations are warranted to validate the modification effect of plasma L-aspartic acid levels on GC prevention and to elucidate the underlying mechanisms.展开更多
This study presents a novel approach to improving the anticorrosive performance of AZ31 Mg alloy by exploiting the role of the hydration reaction to induce interactions between Quinolin-8-ol(8HQ)molecules and the poro...This study presents a novel approach to improving the anticorrosive performance of AZ31 Mg alloy by exploiting the role of the hydration reaction to induce interactions between Quinolin-8-ol(8HQ)molecules and the porous MgO layer formed via plasma electrolytic oxidation(PEO).The AZ31 Mg alloy,initially coated with a PEO layer,underwent a dipping treatment in an ethanolic solution of 0.05 M 8HQ at 50℃ for 3 h.The results were compared with those from a different procedure where the PEO layer was subjected to a hydration reaction for 2 h at 90℃ before immersion in the 8HQ solution under the same conditions.The hydration treatment played a crucial role by converting MgO to Mg(OH)_(2),significantly enhancing the surface reactivity.This transformation introduced hydroxyl groups(−OH)on the surface,which facilitated donor-acceptor interactions with the electron-accepting sites on 8HQ molecules.The calculated binding energy(Ebinding)from DFT indicated that the interaction energy of 8HQ with Mg(OH)_(2) was lower compared to 8HQ with MgO,suggesting easier adsorption of 8HQ molecules on the hydrated surface.This,combined with the increased number of active sites and enhanced surface area,allowed for extensive surface coverage by 8HQ,leading to the formation of a stable,flake-like protective layer that sealed the majority of pores on the PEO layer.DFT calculations further suggested that the hydration treatment provided multiple active sites,enabling effective contact with 8HQ and rapid electron transfer,creating ideal conditions for charge-transfer-induced physical and chemical bonding.This study shows that hydration and 8HQ treatments significantly enhance the corrosion resistance of Mg alloys,highlighting their potential for advanced anticorrosive coatings.展开更多
BACKGROUND Skin wounds are common injuries that affect quality of life and incur high costs.A considerable portion of healthcare resources in Western countries is allocated to wound treatment,mainly using mechanical,b...BACKGROUND Skin wounds are common injuries that affect quality of life and incur high costs.A considerable portion of healthcare resources in Western countries is allocated to wound treatment,mainly using mechanical,biological,or artificial dressings.Biological and artificial dressings,such as hydrogels,are preferred for their biocompatibility.Platelet concentrates,such as platelet-rich plasma(PRP)and platelet-rich fibrin(PRF),stand out for accelerating tissue repair and minimizing risks of allergies and rejection.This study developed PRF and PRP-based dressings to treat skin wounds in an animal model,evaluating their functionality and efficiency in accelerating the tissue repair process.AIM To develop wound dressings based on platelet concentrates and evaluating their efficiency in treating skin wounds in Wistar rats.METHODS Wistar rats,both male and female,were subjected to the creation of a skin wound,distributed into groups(n=64/group),and treated with Carbopol(negative control);PRP+Carbopol;PRF+Carbopol;or PRF+CaCl_(2)+Carbopol,on days zero(D0),D3,D7,D14,and D21.PRP and PRF were obtained only from male rats.On D3,D7,D14,and D21,the wounds were analyzed for area,contraction rate,and histopathology of the tissue repair process.RESULTS The PRF-based dressing was more effective in accelerating wound closure early in the tissue repair process(up to D7),while PRF+CaCl_(2) seemed to delay the process,as wound closure was not complete by D21.Regarding macroscopic parameters,animals treated with PRF+CaCl_(2) showed significantly more crusting(necrosis)early in the repair process(D3).In terms of histopathological parameters,the PRF group exhibited significant collagenization at the later stages of the repair process(D14 and D21).By D21,fibroblast proliferation and inflammatory infiltration were higher in the PRP group.Animals treated with PRF+CaCl_(2) experienced a more pronounced inflammatory response up to D7,which diminished from D14 onwards.CONCLUSION The PRF-based dressing was effective in accelerating the closure of cutaneous wounds in Wistar rats early in the process and in aiding tissue repair at the later stages.展开更多
The formation of an embedded electron current sheet within the magnetotail plasma sheet has been poorly understood.In this article,we present an electron current layer detected at the edge of the magnetotail plasma sh...The formation of an embedded electron current sheet within the magnetotail plasma sheet has been poorly understood.In this article,we present an electron current layer detected at the edge of the magnetotail plasma sheet.The ions were demagnetized inside the electron current layer,but the electrons were still frozen in with the magnetic field line.Thus,this decoupling of ions and electrons gave rise to a strong Hall electric field,which could be the reason for the formation of the embedded thin current layer.The magnetized electrons,the absence of the nongyrotropic electron distribution,and negligible energy dissipation in the layer indicate that magnetic reconnection had not been triggered within the embedded thin current layer.The highly asymmetric plasma on the two sides of the current layer and low magnetic shear across it could suppress magnetic reconnection.The observations indicate that the embedded electric current layer,probably generated by the Hall electric field,even down to electron scale,is not a sufficient condition for magnetic reconnection.展开更多
This paper highlights the crucial role of Indonesia’s GNSS receiver network in advancing Equatorial Plasma Bubble(EPB)studies in Southeast and East Asia,as ionospheric irregularities within EPB can disrupt GNSS signa...This paper highlights the crucial role of Indonesia’s GNSS receiver network in advancing Equatorial Plasma Bubble(EPB)studies in Southeast and East Asia,as ionospheric irregularities within EPB can disrupt GNSS signals and degrade positioning accuracy.Managed by the Indonesian Geospatial Information Agency(BIG),the Indonesia Continuously Operating Reference Station(Ina-CORS)network comprises over 300 GNSS receivers spanning equatorial to southern low-latitude regions.Ina-CORS is uniquely situated to monitor EPB generation,zonal drift,and dissipation across Southeast Asia.We provide a practical tool for EPB research,by sharing two-dimensional rate of Total Electron Content(TEC)change index(ROTI)derived from this network.We generate ROTI maps with a 10-minute resolution,and samples from May 2024 are publicly available for further scientific research.Two preliminary findings from the ROTI maps of Ina-CORS are noteworthy.First,the Ina-CORS ROTI maps reveal that the irregularities within a broader EPB structure persist longer,increasing the potential for these irregularities to migrate farther eastward.Second,we demonstrate that combined ROTI maps from Ina-CORS and GNSS receivers in East Asia and Australia can be used to monitor the development of ionospheric irregularities in Southeast and East Asia.We have demonstrated the combined ROTI maps to capture the development of ionospheric irregularities in the Southeast/East Asian sector during the G5 Geomagnetic Storm on May 11,2024.We observed simultaneous ionospheric irregularities in Japan and Australia,respectively propagating northwestward and southwestward,before midnight,whereas Southeast Asia’s equatorial and low-latitude regions exhibited irregularities post-midnight.By sharing ROTI maps from Indonesia and integrating them with regional GNSS networks,researchers can conduct comprehensive EPB studies,enhancing the understanding of EPB behavior across Southeast and East Asia and contributing significantly to ionospheric research.展开更多
基金support from UGC-SAP (DRS, Phase Ⅲ) with Sanction order No. F.510/3/DRS-Ⅲ/2015(SAPI)UGC-MRP with F. No. 43-539/2014 (SR)FD Diary No.3668
文摘The propagation characteristics of nonlinear ion–acoustic（IA） solitary waves（SWs） are studied in thermal electron–positron–ion plasma considering the effect of relativistic positron beam. Starting from a set of fluid equations and using the reductive perturbation technique, we derive a Korteweg–de Vries（KdV） equation which governs the evolution of weakly nonlinear IA SWs in relativistic beam driven plasmas. The properties of the IA soliton are studied, and it is shown that the presence of relativistic positron beam significantly modifies the characteristics of IA solitons.
文摘A rigorous theoretical investigation is made of ion-acoustic shock structures in an unmagnetized three-component plasma whose constituents are nonextensive electrons, nonextensive positrons, and inertial ions. The Burgers equation is derived by employing the reductive perturbation method. The effects of electron and positron nonextensivity and ion kinematic viscosity on the properties of these ion-acoustic shock waves are briefly discussed. It is found that shock waves with positive and negative potentials are obtained to depend on the plasma parameters. The entailment of our results may be useful to understand some astrophysical and cosmological scenarios including stellar polytropes, hadronic matter and quark-gluon plasma, protoneutron stars, dark-matter halos, etc., where effects of nonextensivity can play significant roles.
文摘Electron-acoustic shock waves （EASWs） in an unmagnetized four-component plasma （containing hot elec- trons and positrons following the q-nonextensiv.e distribution, cold mobile viscous electron fluid, and immobile positive ions） are studied in nonplanar （cylindrical and spherical） geometry. With the help of the reductive perturbation method, the modified Burgers equation is derived. Analytically, the effects of nonplanar geometry, nonextensivity, relative number density and temperature ratios, and cold electron kinematic viscosity on the basic properties （viz. amplitude, width, speed, etc.） of EASWs are discussed. It is exarmined that the EASWs in nonplanar geometry significantly differ from those in planar geometry. The results of this investigation can be helpful in understanding the nonlinear features of EASWs in various astrophysical plasmas.
文摘Ion-acoustic solitary (IAS) waves in electron-positron-ion (e-p-i) plasma have been of interest to many researchers probably due to their relevance in understanding the Universe. However, the study of non-linear ion-acoustic waves in e-p-i plasma with non-thermal electrons has not been adequately studied. A theoretical investigation on non-linear IAS waves in e-p-i plasma comprising of warm inertial adiabatic fluid ions and electrons that are kappa distributed, and Boltzman distributed positron is presented here using the Sagdeev potential technique. It was found that existence domains of finite amplitude IAS waves were confined within the limits of minimum and maximum Mach numbers with varying k values. For lower values of k, the amplitude of the solitary electrostatic potential structures increased as the width decreased, while for high values, the potential amplitude decreased as the width of the solitary structure increased.
基金supported by National Natural Science Foundation of China (Nos. 11665012 and 11247016)the Natural Science Foundation of Jiangxi Province, China (Nos. 2014ZBAB202001 and 2015ZBAB202006)
文摘The space-time evolution of a given density perturbation in cold homogeneous electron- positron-ion plasma is investigated with an assumption of infinitely massive ions by employing a numerical calculation method. The phase-mixing time and wave-breaking time can be effectively distinguished with this method. It is found that an increase of the ratio of equilibrium ion density to equilibrium electron density can attenuate plasma oscillations, leading to a delay in wave breaking. The dependence of the phase-mixing and wave-breaking times on the amplitude of the initial perturbation is also discussed.
文摘The nonlinear propagation of waves (specially solitary waves) in an ultra-relativistic degenerate dense plasma (containing ultra-relativistic degenerate electrons and positrons, cold, mobile, inertial ions, and negatively charged static dust) have been investigated by the reductive perturbation method. The linear dispersion relation and Korteweg de-Vries equation have been derived whose numerical solutions have been analyzed to identify the basic features of electrostatic solitary structures that may form in such a degenerate dense plasma. The existence of solitary structures has been also verified by employing the pseudo-potential method. The implications of our results in astrophysical compact objects have been briefly discussed.
基金supported by the Research Foundation for Young Teachers of Hexi University,China (Grant No. QN-201004)
文摘This paper discusses the existence of ion-acoustic solitary waves and their interaction in a dense quantum electron positron-ion plasma by using the quantum hydrodynamic equations. The extended Poincar^-Lighthill-Kuo perturbation method is used to derive the Korteweg-de Vries equations for quantum ion-acoustic solitary waves in this plasma. The effects of the ratio of positrons to ions unperturbation number density p and the quantum diffraction parameter He （Hp） on the newly formed wave during interaction, and the phase shift of the colliding solitary waves are studied. It is found that the interaction between two solitary waves fits linear superposition principle and these plasma parameters have significantly influence on the newly formed wave and phase shift of the colliding solitary waves. The investigations should be useful for understanding the propagation and interaction of ion-acoustic solitary waves in dense astrophysical plasmas （such as white dwarfs） as well as in intense laser-solid matter interaction experiments.
基金Supported by Quaid-i-Azam University Research Fund,URF Project No.URF/(2007-2009)
文摘The formation and propagation of shocks and solitons are investigated in an unmagnetized, ultradense plasma containing degenerate Fermi gas of electrons and positrons, and classical ion gas by employing Thomas-Fermi model. For this purpose, a deformed Korteweg-de Vries-Berger （dKdVB） equation is derived using the reductive perturbative technique for cold, adiabatic, and isothermal ions. Localized analytical solutions of dKdVB equation in planar geometry are obtained for dispersion as well as dissipation dominant cases. For nonplanar （cylindrical and spherical） geometry, time varying numerical shock wave solution of dKdVB equation is found. Its dispersion dominant case leading to the soliton solution is also discussed. The effect of ion temperature, positron concentration and dissipation is found significant on these nonlinear structures. The relevance of the results to the systems of scientific interest is pointed out.
文摘The basic properties of the nonlinear propagation of the nonplanar （cylindrical and spherical） positronacoustic （PA） shock waves （SHWs） in an unmagnetized electron-positron-ion （e-p-i） plasma containing immobile positive ions, mobile cold positrons, and superthermal （kappa distributed） hot positrons and electrons are investigated both analytically and numerically. The modified Burgers equation （roBE） is derived by using the reductive perturbation method. The basic features of PA SHWs are significantly modified by the cold positron kinematic viscosity （U）, superthermal parameter of electrons （ke）, superthermal parameter of hot positrons （kp）, the ratio of the electron temperature to hot positron temperature （or）, the ratio of the electron number density to cold positron number density （μe）, and the ratio of the hot positron number density to cold positron number density （μph）. This study could be useful to identify the basic properties of nonlinear electrostatic disturbances in dissipative space and laboratory plasmas.
基金financially supported by the National Natural Science Foundation of China(No.52204284)the China Postdoctoral Science Foundation(No.2025MD784125)+2 种基金the Natural Science Foundation of Shaanxi Province,China(No.2024JC-YBQN-0365)the Shaanxi Province Postdoctoral Science Foundation,China(No.2025BSHSDZZ363)Outstanding Youth Science Fund of Xi’an University of Science and Technology,China(No.202308)。
文摘Interfacial interactions between rough mineral particles have garnered considerable attention as they directly determine particle agglomeration and floatability.This study comprehensively investigates the agglomeration characteristics of siderite particles after argon(Ar)plasma surface modification through settling tests,flocs size measurements,and fractal dimension calculations.Ar plasma surface modification promotes the agglomeration of siderite particles,as evidenced by increased floc size and density.The agglomeration mechanism induced by Ar plasma surface modification is evaluated using a theoretical model combining the surface element integration(SEI)approach,differential geometry,and the composite Simpson's rule.Changes in surface roughness,wettability,and charge are considered in this model.Compared to the unpretreated siderite particles,the energy barrier for interaction of the 30-min Ar plasma-pretreated siderite particles decreases from 2.3×10-^(17)J to 1.6×10^(-17)J.This reduction provides strong evidence for the agglomeration behavior of siderite particles.Furthermore,flotation experiments confirm that Ar plasma surface modification is conducive to the aggregation flotation of siderite.These findings offer crucial insights into particle aggregation and dispersion behaviors,with notable application in mineral flotation.
文摘This study investigated enhancing the wear resistance of Ti6Al4V alloys for medical applications by incorporating Ti C nanoreinforcements using advanced spark plasma sintering(SPS). The addition of up to 2.5wt% Ti C significantly improved the mechanical properties, including a notable 18.2% increase in hardness(HV 332). Fretting wear tests against 316L stainless steel(SS316L) balls demonstrated a 20wt%–22wt% reduction in wear volume in the Ti6Al4V/Ti C composites compared with the monolithic alloy. Microstructural analysis revealed that Ti C reinforcement controlled the grain orientation and reduced the β-phase content, which contributed to enhanced mechanical properties. The monolithic alloy exhibited a Widmanstätten lamellar microstructure, while increasing the Ti C content modified the wear mechanisms from ploughing and adhesion(0–0.5wt%) to pitting and abrasion(1wt%–2.5wt%). At higher reinforcement levels, the formation of a robust oxide layer through tribo-oxide treatment effectively reduced the wear volume by minimizing the abrasive effects and plastic deformation. This study highlights the potential of SPS-mediated Ti C reinforcement as a transformative approach for improving the performance of Ti6Al4V alloys, paving the way for advanced medical applications.
文摘The nonlinear features of two-dimensional ion acoustic(IA) solitary and shock structures in a dissipative electron-positron-ion(EPI) quantum plasma are investigated. The dissipation in the system is taken into account by incorporating the kinematic viscosity of ions in plasmas. A quantum hydrodynamic(QHD) model is used to describe the quantum plasma system. The propagation of small but finite amplitude solitons and shocks is governed by the Kadomtsev-Petviashvili-Burger(KPB) equation. It is observed that depending on the values of plasma parameters(viz.quantum diffraction, positron concentration, viscosity), both compressive and rarefactive solitons and shocks are found to exist. Furthermore, the energy of the soliton is computed and possible solutions of the KPB equation are presented numerically in terms of the monotonic and oscillatory shock profiles
基金supported by the National Natural Science Foundation of China(52375437,52035009)the Natural Science Foundation of Guangdong Province(2024B1515020027)+2 种基金the Shenzhen Science and Technology Program(Grant No.KQTD20170810110250357)for the financial supportthe assistance of SUSTech Core Research Facilitiessupported by Shenzhen Engineering Research Center for Semiconductorspecific Equipment。
文摘The highly efficient manufacturing of atomic-scale smooth β-Ga_(2)O_(3)surface is fairly challenging because β-Ga_(2)O_(3)is a typical difficult-to-machine material.In this study,a novel plasma dry etching method named plasma-based atom-selective etching(PASE)is proposed to achieve the highly efficient,atomic-scale,and damage-free polishing of β-Ga_(2)O_(3).The plasma is excited through the inductive coupling principle and carbon tetrafluoride is utilized as the main reaction gas to etch β-Ga_(2)O_(3).The core of PASE polishing of β-Ga_(2)O_(3)is the remarkable lateral etching effect,which is ensured by both the intrinsic property of the surface and the extrinsic temperature condition.As revealed by density functional theory-based calculations,the intrinsic difference in the etching energy barrier of atoms at the step edge(2.36 eV)and in the terrace plane(4.37 eV)determines their difference in the etching rate,and their etching rate difference can be greatly enlarged by increasing the extrinsic temperature.The polishing of β-Ga_(2)O_(3)based on the lateral etching effect is further verified in the etching experiments.The Sa roughness of β-Ga_(2)O_(3)(001)substrate is reduced from 14.8 nm to 0.057 nm within 120 s,and the corresponding material removal rate reaches up to 20.96μm·min^(−1).The polished β-Ga_(2)O_(3)displays significantly improved crystalline quality and photoluminescence intensity,and the polishing effect of PASE is independent of the crystal face of β-Ga_(2)O_(3).In addition,the competition between chemical etching and physical reconstruction,which is determined by temperature and greatly affects the surface state of β-Ga_(2)O_(3),is deeply studied for the first time.These findings not only demonstrate the high-efficiency and high-quality polishing of β-Ga_(2)O_(3)via atmospheric plasma etching but also hold significant implications for guiding future plasma-based surface manufacturing of β-Ga_(2)O_(3).
文摘目的:观察Plasma等离子束联合强脉冲光治疗面部烧伤瘢痕的疗效及对瘢痕评分、疼痛程度的影响。方法:本次研究为前瞻性研究,采用随机数字表法将茂名市人民医院2024年3月至2024年8月期间收治的92例面部烧伤瘢痕患者分为对照组(接受强脉冲光治疗,46例)和研究组(对照组的基础上接受Plasma等离子束治疗,46例)。对比两组疗效、相关量表评分、瘢痕恢复情况和不良反应发生率。结果:和对照组治疗后相比,研究组的临床总有效率和中文版简易烧伤健康量表(chinese version of the simplified burn health scale, BSHS-B)评分更高,温哥华瘢痕量表(vancouver scar scale, VSS)、视觉模拟疼痛量表(visual analogue scale, VAS)评分和瘢痕厚度、瘢痕血流灌注量更低(P<0.05)。两组不良反应发生率组间对比未见差异(P>0.05)。结论:应用Plasma离子束联合强脉冲光治疗面部烧伤瘢痕患者,可提高临床疗效,改善瘢痕厚度和血流灌注量,缓解瘢痕瘙痒及疼痛程度,安全性较好。
基金Supported by the Natural Science Foundation of Heilongjiang Province(LH2024A025)。
文摘The effects of plasma screening on the ^(1)P^(o) resonance states of H-and He below the n=3 and n=4 thresholds of the respective subsystemsare investigated using the stabilization method and correlated exponential wave functions.Two plasma mediums,namely,the Debye plasma and quantum plasma environments are considered.The screened Coulomb potential(SCP)obtained from Debye-Hückel model is used to represent Debye plasma environments and the exponential cosine screened Coulomb potential(ECSCP)obtained from a modified Debye-Hückel model is used to represent quantum plasma environments.The resonance parameters(resonance positions and widths)are presented in terms of the screening parameters.
基金funded by the National Natural Science Foundation of China(No.82273704)Noncommunicable Chronic Diseases-National Science and Technology Major Project(No.2023ZD0501400-2023ZD0501402)+4 种基金Beijing Hospitals Authority’s Ascent Plan(DFL20241102)Beijing Hospitals Authority Clinical Medicine Development of Special Funding Support(No.ZLRK202325)China Postdoctoral Science Foundation(2024M760152)Peking University Medicine Fund for World’s Leading Discipline or Discipline Cluster Development(No.BMU2022XKQ004)Science Foundation of Peking University Cancer Hospital(Nos.BJCH2024BJ02,XKFZ2410,BJCH2025CZ04,and 2022-27)。
文摘Objective:Based on multistage metabolomic profiling and Mendelian randomization analyses,the current study identified plasma metabolites that predicted the risk of developing gastric cancer(GC)and determined whether key metabolite levels modified the GC primary prevention effects.Methods:Plasma metabolites associated with GC risk were identified through a case-control study.Bi-directional two-sample Mendelian randomization analyses were performed to determine potential causal relationships utilizing the Shandong Intervention Trial(SIT),a nested case-control study of the Mass Intervention Trial in Linqu,Shandong province(MITS),China,the UK Biobank,and the Finn Gen project.Results:A higher genetic risk score for plasma L-aspartic acid was significantly associated with an increased GC risk in the northern Chinese population(SIT:HR=1.26 per 1 SD change,95%CI:1.07±1.49;MITS:HR=1.07,95%CI:1.00±1.14)and an increased gastric adenocarcinoma risk in Finn Gen(OR=1.68,95%CI:1.16±2.45).Genetically predicted plasma L-aspartic acid levels also modified the GC primary prevention effects with the beneficial effect of Helicobacter pylori eradication notably observed among individuals within the top quartile of L-aspartic acid level(P-interaction=0.098)and the beneficial effect of garlic supplementation only for those within the lowest quartile of L-aspartic acid level(P-interaction=0.02).Conclusions:Elevated plasma L-aspartic acid levels significantly increased the risk of developing GC and modified the effects of GC primary prevention.Further studies from other populations are warranted to validate the modification effect of plasma L-aspartic acid levels on GC prevention and to elucidate the underlying mechanisms.
基金supported by the National Research Foundation of Korea(NRF)funded by the Korean government(MSIT)(No.2022R1A2C1006743).
文摘This study presents a novel approach to improving the anticorrosive performance of AZ31 Mg alloy by exploiting the role of the hydration reaction to induce interactions between Quinolin-8-ol(8HQ)molecules and the porous MgO layer formed via plasma electrolytic oxidation(PEO).The AZ31 Mg alloy,initially coated with a PEO layer,underwent a dipping treatment in an ethanolic solution of 0.05 M 8HQ at 50℃ for 3 h.The results were compared with those from a different procedure where the PEO layer was subjected to a hydration reaction for 2 h at 90℃ before immersion in the 8HQ solution under the same conditions.The hydration treatment played a crucial role by converting MgO to Mg(OH)_(2),significantly enhancing the surface reactivity.This transformation introduced hydroxyl groups(−OH)on the surface,which facilitated donor-acceptor interactions with the electron-accepting sites on 8HQ molecules.The calculated binding energy(Ebinding)from DFT indicated that the interaction energy of 8HQ with Mg(OH)_(2) was lower compared to 8HQ with MgO,suggesting easier adsorption of 8HQ molecules on the hydrated surface.This,combined with the increased number of active sites and enhanced surface area,allowed for extensive surface coverage by 8HQ,leading to the formation of a stable,flake-like protective layer that sealed the majority of pores on the PEO layer.DFT calculations further suggested that the hydration treatment provided multiple active sites,enabling effective contact with 8HQ and rapid electron transfer,creating ideal conditions for charge-transfer-induced physical and chemical bonding.This study shows that hydration and 8HQ treatments significantly enhance the corrosion resistance of Mg alloys,highlighting their potential for advanced anticorrosive coatings.
文摘BACKGROUND Skin wounds are common injuries that affect quality of life and incur high costs.A considerable portion of healthcare resources in Western countries is allocated to wound treatment,mainly using mechanical,biological,or artificial dressings.Biological and artificial dressings,such as hydrogels,are preferred for their biocompatibility.Platelet concentrates,such as platelet-rich plasma(PRP)and platelet-rich fibrin(PRF),stand out for accelerating tissue repair and minimizing risks of allergies and rejection.This study developed PRF and PRP-based dressings to treat skin wounds in an animal model,evaluating their functionality and efficiency in accelerating the tissue repair process.AIM To develop wound dressings based on platelet concentrates and evaluating their efficiency in treating skin wounds in Wistar rats.METHODS Wistar rats,both male and female,were subjected to the creation of a skin wound,distributed into groups(n=64/group),and treated with Carbopol(negative control);PRP+Carbopol;PRF+Carbopol;or PRF+CaCl_(2)+Carbopol,on days zero(D0),D3,D7,D14,and D21.PRP and PRF were obtained only from male rats.On D3,D7,D14,and D21,the wounds were analyzed for area,contraction rate,and histopathology of the tissue repair process.RESULTS The PRF-based dressing was more effective in accelerating wound closure early in the tissue repair process(up to D7),while PRF+CaCl_(2) seemed to delay the process,as wound closure was not complete by D21.Regarding macroscopic parameters,animals treated with PRF+CaCl_(2) showed significantly more crusting(necrosis)early in the repair process(D3).In terms of histopathological parameters,the PRF group exhibited significant collagenization at the later stages of the repair process(D14 and D21).By D21,fibroblast proliferation and inflammatory infiltration were higher in the PRP group.Animals treated with PRF+CaCl_(2) experienced a more pronounced inflammatory response up to D7,which diminished from D14 onwards.CONCLUSION The PRF-based dressing was effective in accelerating the closure of cutaneous wounds in Wistar rats early in the process and in aiding tissue repair at the later stages.
基金the National Natural Science Founda-tion of China(NSFC,Grant No.42174181)and the Key Research Program of Frontier Sciences,CAS(Grant No.QYZDJ-SSW-DQC010).
文摘The formation of an embedded electron current sheet within the magnetotail plasma sheet has been poorly understood.In this article,we present an electron current layer detected at the edge of the magnetotail plasma sheet.The ions were demagnetized inside the electron current layer,but the electrons were still frozen in with the magnetic field line.Thus,this decoupling of ions and electrons gave rise to a strong Hall electric field,which could be the reason for the formation of the embedded thin current layer.The magnetized electrons,the absence of the nongyrotropic electron distribution,and negligible energy dissipation in the layer indicate that magnetic reconnection had not been triggered within the embedded thin current layer.The highly asymmetric plasma on the two sides of the current layer and low magnetic shear across it could suppress magnetic reconnection.The observations indicate that the embedded electric current layer,probably generated by the Hall electric field,even down to electron scale,is not a sufficient condition for magnetic reconnection.
基金JSPS KAKENHI Grant Number16H06286 supports global GNSS ionospheric maps (TEC,ROTI,and detrended TEC maps) developed by the Institute for SpaceEarth Environmental Research (ISEE) of Nagoya Universitysupport of the 2024 JASSO Follow-up Research Fellowship Program for a 90-day visiting research at the Institute for Space-Earth Environmental Research (ISEE),Nagoya University+3 种基金the support received from Telkom University under the“Skema Penelitian Terapan Periode I Tahun Anggaran 2024”the Memorandum of Understanding for Research Collaboration on Regional Ionospheric Observation (No:092/SAM3/TE-DEK/2021)the National Institute of Information and Communications Technology (NICT) International Exchange Program 2024-2025(No.2024-007)support for a one-year visiting research at Hokkaido University
文摘This paper highlights the crucial role of Indonesia’s GNSS receiver network in advancing Equatorial Plasma Bubble(EPB)studies in Southeast and East Asia,as ionospheric irregularities within EPB can disrupt GNSS signals and degrade positioning accuracy.Managed by the Indonesian Geospatial Information Agency(BIG),the Indonesia Continuously Operating Reference Station(Ina-CORS)network comprises over 300 GNSS receivers spanning equatorial to southern low-latitude regions.Ina-CORS is uniquely situated to monitor EPB generation,zonal drift,and dissipation across Southeast Asia.We provide a practical tool for EPB research,by sharing two-dimensional rate of Total Electron Content(TEC)change index(ROTI)derived from this network.We generate ROTI maps with a 10-minute resolution,and samples from May 2024 are publicly available for further scientific research.Two preliminary findings from the ROTI maps of Ina-CORS are noteworthy.First,the Ina-CORS ROTI maps reveal that the irregularities within a broader EPB structure persist longer,increasing the potential for these irregularities to migrate farther eastward.Second,we demonstrate that combined ROTI maps from Ina-CORS and GNSS receivers in East Asia and Australia can be used to monitor the development of ionospheric irregularities in Southeast and East Asia.We have demonstrated the combined ROTI maps to capture the development of ionospheric irregularities in the Southeast/East Asian sector during the G5 Geomagnetic Storm on May 11,2024.We observed simultaneous ionospheric irregularities in Japan and Australia,respectively propagating northwestward and southwestward,before midnight,whereas Southeast Asia’s equatorial and low-latitude regions exhibited irregularities post-midnight.By sharing ROTI maps from Indonesia and integrating them with regional GNSS networks,researchers can conduct comprehensive EPB studies,enhancing the understanding of EPB behavior across Southeast and East Asia and contributing significantly to ionospheric research.
